Tread on tires becomes shallower as the tires are used. When this occurs, tire performance may change. For example, tires with shallower tread have improved dry pavement performance due to the increased contact area to the road, but worse wet pavement performance if the tires become unable to channel water out. A driver of a vehicle should monitor the wear of the tires on the vehicle, and replace the tires when the level of tread becomes too low.